add squeeze argument to read_csv

[thoo]

Fix #808

Add squeeze argument to DataFrame.read_csv so that it is more aligned with pandas.DataFrame.read_csv and the behavior will be the same as in pandas. Also add pytests for this feature.

[softagram-bot]

Softagram Impact Report for pull/812 (head commit: 0ea693c)

⭐ Change Overview

(Open in Softagram Desktop for full details)

📄 Full report

• Permalink: Full report for pull/812

Impact Report explained. Give feedback on this report to support@softagram.com

[codecov-io]

Codecov Report

Merging #812 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #812      +/-   ##
==========================================
+ Coverage   94.32%   94.33%   +<.01%     
==========================================
  Files          32       32              
  Lines        5837     5840       +3     
==========================================
+ Hits         5506     5509       +3     
  Misses        331      331

Impacted Files	Coverage Δ
databricks/koalas/namespace.py	86.27% <100%> (+0.13%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2363c0b...0ea693c. Read the comment docs.

[HyukjinKwon]

Thanks for the contribution, @thoo

[HyukjinKwon]

Thanks, @thoo